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TRONDHEIM, Norway — Avoiding divorce may be the best thing you can do for your cognitive health, a new study reveals. Researchers in Norway say adults who stay with their spouse throughout middle age are at the lowest risk for dementia onset. On the other hand, getting a divorce or remaining single during these years leads to the highest rates of the disease.

“Exactly what causes dementia is a mystery. This survey indicates that being married and a lower risk of dementia are linked, but we don’t know why,” says Asta Håberg, a doctor at St. Olav’s Hospital and a professor at the Norwegian University of Science and Technology, in a media release.

The team from NTNU and the Norwegian Institute of Public Health examined different types of relationships over a 24-year period. Participants were either married, divorced, or single between the ages of 44 and 68. The team then analyzed if marital status displayed a connection to a diagnosis of dementia or mild cognitive impairment when these individuals turned 70.

Specifically, the team looked at roughly 150,000 people living in the Norwegian county of Nord-Trøndelag who took part in HUNT Study health surveys. Researchers compared incidence of dementia to health factors such as smoking, high blood pressure, obesity, physical inactivity, diabetes, psychological problems, and each person’s number of close friendships.

What is it about marriage which keeps the brain healthy?

“One theory has been that people who are married live healthier lives, and that this explains differences in the risk of various diseases. In this survey, we found no support for health differences between married and unmarried people explaining the difference in dementia risk,” says Håberg. “We thought that these factors would mean something, but they didn’t explain anything.”

Since health doesn’t seem to be the reason, researchers started looking at other factors which are more common among married couples. It turns out that staying together “for the kids” may also benefit a parent’s brain. Researchers found that having children significantly lowered the risk of dementia. Even among unmarried people, having children lowered dementia risk after age 70 by 60 percent.

“Some people have theorized that if you have children, you stay more cognitively engaged. For example, you have to deal with people and participate in activities that you wouldn’t otherwise have to. This stimulates your brain so that it possibly works better. That way you build up a kind of cognitive reserve,” Håberg explains.

What is cognitive reserve?

Study authors explain that a person’s “reserve” is not an actual physical structure in the brain. It won’t show up on an MRI scan or in an autopsy of someone’s brain. Instead, the term refers to a person’s resilience to brain damage and cognitive decline over time. Håberg says this makes it part of the “mystery of dementia.”

“We don’t know whether it’s being married or having children that protects against dementia, or if it’s a case of pre-selection, for example. This would mean that people who have a lower probability of developing dementia also have a higher probability of finding a partner and having children. But the fact that we have the HUNT Study means that we have a lot of data available that we haven’t yet used to investigate this further,” the researcher continues.

“It’s common to think that ‘if you live long enough, sooner or later you’ll develop dementia.’ I’m not so sure I agree with that, given this theory that we may have cognitive reserves.”

The researchers add that certain activities build up someone’s cognitive reserves, forming more connections within the brain. For example, studies show that the more education someone has, the better their reserves look over time — keeping dementia onset away longer. However, researchers note that when a highly educated person develops Alzheimer’s disease (the most common form of dementia), the disease progresses just as fast as it does for a person with lower reserves.

Could marriage affect your genes?

Study authors say their next step in this project is to look at how a married or unmarried person’s genes connect to dementia onset.

“We know that certain genes increase the risk of dementia, but people with these genes can still live to be 90 years old without experiencing cognitive problems,” says Vegard Skirbekk at the Norwegian Institute of Public Health.

“You could say that the increased risk inherent in the genes can be regarded as a vulnerability, where having a stable family life might possibly reduce this vulnerability.”

Skirbekk notes that that this particular study does not examine the biological mechanisms behind dementia.

“But it shows that being married can have an influence on risk factors. You become more cognitively active, you cope better with adversity and are less subject to stress. The partner represents a security that provides a buffer.”

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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